A disposable gas lighter as disclosed in my U.S. Pats. 3,884,616 and 3,884,618 comprises a cylindrical reservoir body containing liquefied butane. An outlet passage has an inner end opening into the interior of the reservoir and an outer end normally covered by a so-called diffuser formed of a block of porous material. The extent of compression of this diffuser determines the rate at which the gas can vaporize and escape from the reservoir. A valve is provided downstream of this diffuser which, when open, allows the gas to escape at the rate determined by the diffuser. A flint-type sparking device allows the escaping gas to be ignited.
In disposable lighters cost is held to a minimum by presetting during production the flame height as determined by the rate of gas passage through the diffuser. Thus the diffuser, usually composed of a coherent body of nonsoluble fibers, is compressed to a predetermined extent during production. This is effected by often relatively complicated measures so that the saving realized by eliminating the flame adjustment is only nominal, and often the preset flame height is incorrect.